Major Histocompatibility Complex Research Articles

Enthesitis as an initial presentation of vascular Behçet's syndrome: a case-based review.

Enthesitis is a characteristic manifestation of spondyloarthropathy (SpA). Historically, Behçet's syndrome (BS) was classified within SpA. Although they are now classified separately, the association between BS and SpA remains controversial. The concept of MHC-I (major histocompatibility complex class I)-opathy has been proposed based on the overlap in immunopathological mechanisms among diseases associated with human leukocyte antigen (HLA) class I. Enthesitis is a frequent complication in patients with BS who also have acne and arthritis. However, information regarding enthesitis in patients with BS without arthritis (BS-WA) is limited. Herein, we report a case of vascular BS complicated by enthesitis. In this case, heel pain was the dominant symptom at presentation. Laboratory tests revealed chlamydia antibody positivity, leading to a tentative diagnosis of reactive arthritis. Despite treatment, C-reactive protein (CRP) levels remained elevated. Imaging revealed numerous aneurysmal lesions in the large vessels. Based on these findings and other symptoms, patient was diagnosed with vascular BS. He tested positive for HLA-B15 and HLA-B46, which are associated with peripheral SpA. Subsequent remission induction therapy for BS was effective and the patient was discharged without complications. Our case and a literature review suggest that there exists a subgroup of BS-WA with a complication of enthesitis, possibly belonging to the spectrum of MHC-I-opathies. It is important to consider BS as a differential diagnosis in patients presenting with enthesitis and to conduct a precise medical history review regarding the symptoms of BS.

Host factors influencing variable symptoms of COVID-19.

Similar to many other viruses, SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) causes various symptoms in individuals who have been exposed to the virus. Individuals exposed to the virus can be asymptomatic, mild, severe, and critical for mortality. Most hypotheses explaining the uncertainty of symptoms are based on innate immunity, which is unclear in explaining some issues. For example, 1. uncertain symptoms of SARS-CoV-2 infection, 2. failure to induce immunity for prevention by vaccines in some individuals, and 3. repeated infections in some individuals. With the ambition of explaining this clearly, this article proposed another perspective to explain the cause of uncertain symptoms in SARS-CoV-2-positive individuals. This could be influenced by host factors with a variety of cellular molecules (viral receptors/co-receptors) and major histocompatibility complex (MHC) polymorphisms, which are crucial factors in explaining this question. Hopefully, this perspective could encourage further research and pave the way for developing new public health policies to deal with COVID-19 and emergent viral epidemics in the future.

Abstract PO1-24-11: Distinct patterns of MHC class I, PD-L1 expression, and T-cell infiltration in different subtypes of ductal carcinoma in situ of the breast

Abstract Background: Ductal carcinoma in situ (DCIS) of the breast encompasses various subtypes with distinct behaviors. Immune cell infiltration within the tumor microenvironment is thought to influence DCIS progression. Tumor-infiltrating lymphocytes (TILs) serve as a surrogate marker for the adaptive immune response. The interaction between programmed death 1 (PD-1) and its ligand PD-L1 suppresses effector T-cell function. Major histocompatibility complex (MHC) class I molecules play a critical role in presenting tumor antigens to cytotoxic T cells. Despite the significance of PD-L1 and MHC class I in immune evasion, limited data exist on their correlation with T-cell infiltration in DCIS subtypes. Methods: Using immunohistochemistry, we examined MHC class I and PD-L1 expression, along with CD3+ and CD8+ T lymphocytes, in 131 DCIS cases through tissue microarrays. DCIS subtypes included hormone receptor-positive (HR+)/human epidermal growth factor 2-negative (HER2-), HR+/HER2+, HR-/HER2+, and triple-negative (TN) subtypes. Results: Among the 128 interpretable cases, the distribution was as follows: HR+/HER2- (50.8%), HR+/HER2+ (14.1%), HR-/HER2+ (26.5%), and TN (8.6%). HER2+ subtypes (HR+/HER2+ and HR-/HER2+) exhibited higher stromal TILs, CD3+ T cells, and CD8+ T cells compared to HR+/HER2- subtype. MHC class I loss was observed in 16.4% (21/128) of cases, with the highest frequency in the HR+/HER2- subtype (29.2%), followed by HR-/HER2+ (5.9%), HR+/HER2+ (0%), and TN (0%) subtypes. DCIS cases lacking MHC class I expression displayed lower stromal CD8+ T cell infiltration than those with intact MHC class I. PD-L1 expression in immune cells (≥1%) was detected in 18.8% (24/128) of cases and correlated with increased stromal TILs, CD3+ T cells, and CD8+ T cells. PD-L1 expression was more prevalent in HER2+ subtypes than in HR+/HER2- subtype. PD-L1-positive DCIS cases mostly retained MHC class I expression (95.8%), except for one case (4.2%) in the HR-/HER2+ subtype. The highest numbers of stromal CD3+ and CD8+ T cells were observed in DCIS cases with intact MHC class I and positive PD-L1 expression. The correlation between MHC class I and PD-L1 expression and infiltration of CD3+ and CD8+ T cells was maintained in HR+/HER2- and HR-/HER2+ subtypes. Notably, tumoral CD3+ and CD8+ T cells showed no significant association with MHC class I or PD-L1 expression. Furthermore, MHC class I and PD-L1 expression did not predict tumor recurrence. Conclusion: We observed distinct patterns of MHC class I and PD-L1 expression and T-cell infiltration among DCIS subtypes. Enhancing our understanding of MHC class I, PD-L1, and immune subsets, including CD8+ T cells, may contribute to the development of immune modulating therapies for DCIS, particularly in the HER2+ subtype. Citation Format: Nah Ihm Kim, Min Ho Park, Ji Shin Lee. Distinct patterns of MHC class I, PD-L1 expression, and T-cell infiltration in different subtypes of ductal carcinoma in situ of the breast [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-24-11.

Abstract PO1-26-06: The effect of localized radiotherapy in combination with chemoimmunotherapy in a humanized triple-negative breast cancer mouse model

Abstract Background: Metastatic triple-negative breast cancer (TNBC) is an aggressive sub-type of breast cancer that is challenging to treat. While the addition of immunotherapy (IT) with pembrolizumab (pembro) to chemotherapy prolongs overall survival in patients with programmed death-ligand 1 positive (PD-L1+) TNBC, few patients obtain long-term benefit. Radiotherapy (RT) can stimulate cellular damage, release of tumor antigens and promote the T cell anti-tumor response including at distant sites (abscopal response) when used with IT. The purpose of this study was to investigate the combination of RT with pembro and paclitaxel (pac) in a TNBC humanized mouse model. Methods: Human Immune System BRGS (BALB/c, Rag2-/-, IL2RγC-/-, NODSIRPa ) mice were engrafted with TNBC MDA-MB-231 cells in bilateral flanks. Treatments included: vehicle, pac 10 mg/kg intra-peritoneal (IP) weekly, pembro 15 mg/kg IP weekly, and RT 8 Gy x 3 fractions every other day the first week of treatment to one-sided tumors (contralateral tumors received no RT). Mice were treated and analyzed in the following groups: vehicle, pac + pembro, RT + pac, and RT + pac + pembro. Treatments began when tumors reached 100-300 mm3 and tumors were measured twice weekly. At the end of study, sera, lymph nodes (LNs), spleen, and tumor tissue were collected for immunohistochemistry, single cell suspensions, and flow cytometry analysis for immune cell populations. Results: All treatment arms resulted in a decrease in tumor volume when compared to vehicle with the greatest reduction in the RT + pac and RT + pac + pembro arms. Combination therapy with RT + paclitaxel (p=0.0002) and RT + pac + pembro (p=0.008) resulted in a statistically significant decrease in specific growth rate (SGR) when compared to vehicle. An abscopal effect was not observed in the non-RT tumors compared to RT-tumors in either group. RT + pembro was associated with an increase in hCD45 T cells in LNs and spleens but not in tumors. In mice that received RT, a decrease was noted in HLA-ABC class I and Intermediate Class II major histocompatibility complex (MHC). In addition, RT-tumors had reduced expression of PD-L1 and polio virus receptor (PVR) and increased expression of PD-1. The percentage of interferon gamma (IFNg+), tumor necrosis factor alpha (TNFa+) CD8+ T cells increased with radiation. This percentage was the highest in the triplet therapy with RT+ pembro + pac. Conclusion: Combination treatment with RT + immunochemotherapy resulted in a significant increase in anti-tumor activity when compared to immunochemotherapy alone, however, an abscopal effect was not observed in contralateral non-RT tumors. RT resulted in down-regulation of immune inhibitory receptors and tumor MHC. Citation Format: Anna Schreiber, Stacey Bagby, Stephen Smoots, Adrian Dominguez, Christine Fisher, Julie Lang, Todd Pitts, Jennifer Diamond. The effect of localized radiotherapy in combination with chemoimmunotherapy in a humanized triple-negative breast cancer mouse model [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-26-06.

Combination of S1-N-Terminal and S1-C-Terminal Domain Antigens Targeting Double Receptor-Binding Domains Bolsters Protective Immunity of a Nanoparticle Vaccine against Porcine Epidemic Diarrhea Virus.

Variants of coronavirus porcine epidemic diarrhea virus (PEDV) frequently emerge, causing an incomplete match between the vaccine and variant strains, which affects vaccine efficacy. Designing vaccines with rapidly replaceable antigens and high efficacy is a promising strategy for the prevention of infection with PEDV variant strains. In our study, three different types of self-assembled nanoparticles (nps) targeting receptor-binding N-terminal domain (NTD) and C-terminal domain (CTD) of S1 protein, named NTDnps, CTDnps, and NTD/CTDnps, were constructed and evaluated as vaccine candidates against PEDV. NTDnps and CTDnps vaccines mediated significantly higher neutralizing antibody (NAb) titers than NTD and CTD recombinant proteins in mice. The NTD/CTDnps in varying ratios elicited significantly higher NAb titers when compared with NTDnps and CTDnps alone. The NTD/CTDnps (3:1) elicited NAb with titers up to 92.92% of those induced by the commercial vaccine. Piglets immunized with NTD/CTDnps (3:1) achieved a passive immune protection rate of 83.33% of that induced by the commercial vaccine. NTD/CTDnps (3:1) enhanced the capacity of mononuclear macrophages and dendritic cells to take up and present antigens by activating major histocompatibility complex I and II molecules to stimulate humoral and cellular immunity. These data reveal that a combination of S1-NTD and S1-CTD antigens targeting double receptor-binding domains strengthens the protective immunity of nanoparticle vaccines against PEDV. Our findings will provide a promising vaccine candidate against PEDV.

A cleaved adhesin DNA vaccine targeting dendritic cell against Porphyromonas gingivalis-induced periodontal disease.

Arg-gingipain A (RgpA) is the primary virulence factor of Porphyromonas gingivalis and contains hemagglutinin adhesin (HA), which helps bacteria adhere to cells and proteins. Hemagglutinin's functional domains include cleaved adhesin (CA), which acts as a hemagglutination and hemoglobin-binding actor. Here, we confirmed that the HA and CA genes are immunogenic, and using adjuvant chemokine to target dendritic cells (DCs) enhanced protective autoimmunity against P. gingivalis-induced periodontal disease. C57 mice were immunized prophylactically with pVAX1-CA, pVAX1-HA, pVAX1, and phosphate-buffered saline (PBS) through intramuscular injection every 2 weeks for a total of three administrations before P. gingivalis-induced periodontitis. The DCs were analyzed using flow cytometry and ribonucleic acid sequencing (RNA-seq) transcriptomic assays following transfection with CA lentivirus. The efficacy of the co-delivered molecular adjuvant CA DNA vaccine was evaluated in vivo using flow cytometry, immunofluorescence techniques, and micro-computed tomography. After the immunization, both the pVAX1-CA and pVAX1-HA groups exhibited significantly elevated P. gingivalis-specific IgG and IgG1, as well as a reduction in bone loss around periodontitis-affected teeth, compared to the pVAX1 and PBS groups (p<0.05). The expression of CA promoted the secretion of HLA, CD86, CD83, and DC-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) in DCs. Furthermore, the RNA-seq analysis revealed a significant increase in the chemokine (C-C motif) ligand 19 (p<0.05). A notable elevation in the quantities of DCs co-labeled with CD11c and major histocompatibility complex class II, along with an increase in interferon-gamma (IFN-γ) cells, was observed in the inguinal lymph nodes of mice subjected to CCL19-CA immunization. This outcome effectively illustrated the preservation of peri-implant bone mass in rats afflicted with P. gingivalis-induced peri-implantitis (p<0.05). The co-administration of a CCL19-conjugated CA DNA vaccine holds promise as an innovative and targeted immunization strategy against P. gingivalis-induced periodontitis and peri-implantitis.

Genome-Wide Association Study Identifies IFIH1 and HLA-DQB1*05:02 Loci Associated With Anti-NMDAR Encephalitis.

Anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis is a rare autoimmune neurologic disorder, the genetic etiology of which remains poorly understood. Our study aims to investigate the genetic basis of this disease in the Chinese Han population. We performed a genome-wide association study and fine-mapping study within the major histocompatibility complex (MHC) region of 413 Chinese patients with anti-NMDAR encephalitis recruited from 6 large tertiary hospitals and 7,127 healthy controls. Our genome-wide association analysis identified a strong association at the IFIH1 locus on chromosome 2q24.2 (rs3747517, p = 1.06 × 10-8, OR = 1.55, 95% CI, 1.34-1.80), outside of the human leukocyte antigen (HLA) region. Furthermore, through a fine-mapping study of the MHC region, we discovered associations for 3 specific HLA class I and II alleles. Notably, HLA-DQB1*05:02 (p = 1.43 × 10-12; OR, 2.10; 95% CI 1.70-2.59) demonstrates the strongest association among classical HLA alleles, closely followed by HLA-A*11:01 (p = 4.36 × 10-7; OR, 1.52; 95% CI 1.29-1.79) and HLA-A*02:07 (p = 1.28 × 10-8; OR, 1.87; 95% CI 1.50-2.31). In addition, we uncovered 2 main HLA amino acid variation associated with anti-NMDAR encephalitis including HLA-DQβ1-126H (p = 1.43 × 10-12; OR, 2.10; 95% CI 1.70-2.59), exhibiting a predisposing effect, and HLA-B-97R (p = 3.40 × 10-8; OR, 0.63; 95% CI 0.53-0.74), conferring a protective effect. Computational docking analysis suggested a close relationship between the NR1 subunit of NMDAR and DQB1*05:02. Our findings indicate that genetic variation in IFIH1, involved in the type I interferon signaling pathway and innate immunity, along with variations in the HLA class I and class II genes, has substantial implications for the susceptibility to anti-NMDAR encephalitis in the Chinese Han population.

The potential and promise for clinical application of adoptive T cell therapy in cancer.

Adoptive cell therapy has revolutionized cancer treatment, especially for hematologic malignancies. T cells are the most extensively utilized cells in adoptive cell therapy. Currently, tumor-infiltrating lymphocytes, T cell receptor-transgenic T cells and chimeric antigen receptor T cells are the three main adoptive T cell therapies. Tumor-infiltrating lymphocytes kill tumors by reinfusing enlarged lymphocytes that naturally target tumor-specific antigens into the patient. T cell receptor-transgenic T cells have the ability to specifically destroy tumor cells via the precise recognition of exogenous T cell receptors with major histocompatibility complex. Chimeric antigen receptor T cells transfer genes with specific antigen recognition structural domains and T cell activation signals into T cells, allowing T cells to attack tumors without the assistance of major histocompatibility complex. Many barriers have been demonstrated to affect the clinical efficacy of adoptive T cell therapy, such as tumor heterogeneity and antigen loss, hard trafficking and infiltration, immunosuppressive tumor microenvironment and T cell exhaustion. Several strategies to improve the efficacy of adoptive T cell therapy have been explored, including multispecific chimeric antigen receptor T cell therapy, combination with immune checkpoint blockade, targeting the immunosuppressive tumor microenvironment, etc. In this review, we will summarize the current status and clinical application, followed by major bottlenecks in adoptive T cell therapy. In addition, we will discuss the promising strategies to improve adoptive T cell therapy. Adoptive T cell therapy will result in even more incredible advancements in solid tumors if the aforementioned problems can be handled.

EGC enhances tumor antigen presentation and CD8+ T cell-mediated antitumor immunity via targeting oncoprotein SND1.

The Staphylococcal nuclease and Tudor domain containing 1 (SND1) has been identified as an oncoprotein. Our previous study demonstrated that SND1 impedes the major histocompatibility complex class I (MHC-I) assembly by hijacking the nascent heavy chain of MHC-I to endoplasmic reticulum-associated degradation. Herein, we aimed to identify inhibitors to block SND1-MHC-I binding, to facilitate the MHC-I presentation and tumor immunotherapy. Our findings validated the importance of the K490-containing sites in SND1-MHC-I complex. Through structure-based virtual screening and docking analysis, (-)-Epigallocatechin (EGC) exhibited the highest docking score to prevent the binding of MHC-I to SND1 by altering the spatial conformation of SND1. Additionally, EGC treatment resulted in increased expression levels of membrane-presented MHC-I in tumor cells. The C57BL/6J murine orthotopic melanoma model validated that EGC increases infiltration and activity of CD8+ T cells in both the tumor and spleen. Furthermore, the combination of EGC with programmed death-1 (PD-1) antibody demonstrated a superior antitumor effect. In summary, we identified EGC as a novel inhibitor of SND1-MHC-I interaction, prompting MHC-I presentation to improve CD8+ T cell response within the tumor microenvironment. This discovery presents a promising immunotherapeutic candidate for tumors.

Constitutive Flt3 signaling impacts conventional dendritic cell function.

The development of dendritic cells (DCs) depends on signaling via the FMS-like tyrosine kinase 3 (Flt3) receptor. How Flt3 signaling impacts terminally differentiated DC function is unknown. This is important given the increasing interest in exploiting Flt3 for vaccination and tumor immunotherapy. Here, we examined DCs in mice harboring constitutively activated Flt3 (Flt3-ITD). Flt3ITD/ITD mice possessed expanded splenic DC subsets including plasmacytoid DC, conventional DC (cDC)1, cDC2, double positive (DP) cDC1 (CD11c+ CD8+ CD11b- CD103+ CD86+), noncanonical (NC) cDC1 (CD11c+ CD8+ CD11b- CD103- CD86-) and single positive (SP) cDC1 (CD11c+ CD8+ CD11b- CD103- CD86+). Outcomes of constitutive Flt3 signaling differed depending on the cDC subset examined. In comparison with wild type (WT) DCs, all Flt3ITD/ITD cDCs displayed an altered surface phenotype with changes in costimulatory molecules, major histocompatibility complex class I (MHC I) and II (MHC II). Cytokine secretion patterns, antigen uptake, antigen proteolysis and antigen presenting function differed between WT and Flt3ITD/ITD subsets, particularly cDC2. In summary, Flt3 signaling impacts the function of terminally differentiated cDCs with important consequences for antigen presentation.

HCMV US2 co-opts TRC8 to degrade the endoplasmic reticulum-resident protein LMAN2L.

The human cytomegalovirus (HCMV) pUS2 glycoprotein exploits the host's endoplasmic reticulum (ER)-associated degradation (ERAD) pathway to degrade major histocompatibility complex class I (MHC-I) and prevent antigen presentation. Beyond MHC-I, pUS2 has been shown to target a range of cellular proteins for degradation, preventing their cell surface expression. Here we have identified a novel pUS2 target, ER-resident protein lectin mannose binding 2 like (LMAN2L). pUS2 expression was both necessary and sufficient for the downregulation of LMAN2L, which was dependent on the cellular E3 ligase TRC8. Given the hypothesized role of LMAN2L in the trafficking of glycoproteins, we employed proteomic plasma membrane profiling to measure LMAN2L-dependent changes at the cell surface. A known pUS2 target, integrin alpha-6 (ITGA6), was downregulated from the surface of LMAN2L-deficient cells, but not other integrins. Overall, these results suggest a novel strategy of pUS2-mediated protein degradation whereby pUS2 targets LMAN2L to impair trafficking of ITGA6. Given that pUS2 can directly target other integrins, we propose that this single viral protein may exhibit both direct and indirect mechanisms to downregulate key cell surface molecules.

Structural insights into human MHC-II association with invariant chain

The loading of processed peptides on to major histocompatibility complex II (MHC-II) molecules for recognition by T cells is vital to cell-mediated adaptive immunity. As part of this process, MHC-II associates with the invariant chain (Ii) during biosynthesis in the endoplasmic reticulum to prevent premature peptide loading and to serve as a scaffold for subsequent proteolytic processing into MHC-II-CLIP. Cryo-electron microscopy structures of full-length Human Leukocyte Antigen-DR (HLA-DR) and HLA-DQ complexes associated with Ii, resolved at 3.0 to 3.1 Å, elucidate the trimeric assembly of the HLA/Ii complex and define atomic-level interactions between HLA, Ii transmembrane domains, loop domains, and class II-associated invariant chain peptides (CLIP). Together with previous structures of MHC-II peptide loading intermediates DO and DM, our findings complete the structural path governing class II antigen presentation.

Immunopeptidome mining reveals a novel ERS-induced target in T1D.

Autoreactive CD8+ T cells play a key role in type 1 diabetes (T1D), but the antigen spectrum that activates autoreactive CD8+ T cells remains unclear. Endoplasmic reticulum stress (ERS) has been implicated in β-cell autoantigen generation. Here, we analyzed the major histocompatibility complex class I (MHC-I)-associated immunopeptidome (MIP) of islet β-cells under steady and ERS conditions and found that ERS reshaped the MIP of β-cells and promoted the MHC-I presentation of a panel of conventional self-peptides. Among them, OTUB258-66 showed immunodominance, and the corresponding autoreactive CD8+ T cells were diabetogenic in nonobese diabetic (NOD) mice. High glucose intake upregulated pancreatic OTUB2 expression and amplified the OTUB258-66-specific CD8+ T-cell response in NOD mice. Repeated OTUB258-66 administration significantly reduced the incidence of T1D in NOD mice. Interestingly, peripheral blood mononuclear cells (PBMCs) from patients with T1D, but not from healthy controls, showed a positive IFN-γ response to human OTUB2 peptides. This study provides not only a new explanation for the role of ERS in promoting β-cell-targeted autoimmunity but also a potential target for the prevention and treatment of T1D. The data are available via ProteomeXchange with the identifier PXD041227.

Venous thromboembolism and severe COVID-19: a Mendelian randomization trial and transcriptomic analysis

IntroductionVenous thromboembolism (VTE) is known to be intricately linked to severe COVID-19 (sCOVID-19) occurrence. Herein, we employed univariable Mendelian randomization (MR) and transcriptome analysis to predict the causal association and associated signaling networks between VTE and sCOVID-19.MethodsPotential VTE and sCOVID-19 association was assessed using MR-Egger, weighted median, simple mode, weighted mode, and inverse variance weighted (IVW) regression. We conducted independent univariable analyses involving VTE and sCOVID-19. Using heterogeneity, pleiotropy, and the Leave-One-Out examinations, we performed sensitivity analyses. Thereafter, we performed transcriptome analysis of the GSE164805 dataset to identify differentially expressed genes (DEGs) linked to single nucleotide polymorphisms (SNPs). Lastly, we conducted immune analyses.ResultsBased on our univariable analysis, VTE was a strong indicator of sCOVID-19 development, and it was intricately linked to sCOVID-19. We further conducted sensitivity analysis to demonstrate the reliability of our results. Using differential analysis, we identified 15 major genes, namely, ACSS2, CEP250, CYP4V2, DDB2, EIF6, GBGT1, GSS, MADD, MAPK8IP1, MMP24, YBPC3, NT5DC3, PROCR, SURF6, and YIPF2, which were strongly connected to suppressive adaptive immune as well as augmented inflammatory cells. In addition, we uncovered strong associations with most differential immunologic gene sets, such as, the Major Histocompatibility Complex (MHC), immunoactivators, and immunosuppressors.ConclusionHerein, we demonstrated we strong association between VTE and enhanced sCOVID-19 risk. We also identified 15 DEGs which potentially contribute to the shared immunologic pathogenesis between VTE and sCOVID-19.

Antigen presentation plays positive roles in the regenerative response to cardiac injury in zebrafish

In contrast to adult mammals, adult zebrafish can fully regenerate injured cardiac tissue, and this regeneration process requires an adequate and tightly controlled immune response. However, which components of the immune response are required during regeneration is unclear. Here, we report positive roles for the antigen presentation-adaptive immunity axis during zebrafish cardiac regeneration. We find that following the initial innate immune response, activated endocardial cells (EdCs), as well as immune cells, start expressing antigen presentation genes. We also observe that T helper cells, a.k.a. Cd4+ T cells, lie in close physical proximity to these antigen-presenting EdCs. We targeted Major Histocompatibility Complex (MHC) class II antigen presentation by generating cd74a; cd74b mutants, which display a defective immune response. In these mutants, Cd4+ T cells and activated EdCs fail to efficiently populate the injured tissue and EdC proliferation is significantly decreased. cd74a; cd74b mutants exhibit additional defects in cardiac regeneration including reduced cardiomyocyte dedifferentiation and proliferation. Notably, Cd74 also becomes activated in neonatal mouse EdCs following cardiac injury. Altogether, these findings point to positive roles for antigen presentation during cardiac regeneration, potentially involving interactions between activated EdCs, classical antigen-presenting cells, and Cd4+ T cells.

Multiplex Detection of Seven Staphylococcal Enterotoxins Using Liquid Chromatography–Mass Spectrometry Combined with a Novel Capture Molecule

Food poisoning caused by Staphylococcal enterotoxins (SEs) is prevalent globally, making efficient detection of these toxins very important. Traditionally, liquid chromatography–mass spectrometry required immunosorbent enrichment by magnetic bead-coupled antibodies obtained by animal-specific immunization. However, this method is time-consuming and costly. In this study, two recombinant protein capture molecules were designed based on the principle of toxins binding to Major Histocompatibility Complex (MHCII) and T cell receptor (TCR) molecules. The two capture molecules are called MHCII and MHCII-D10. The design of the MHCII and TCR-D10 was achieved through searching for the binding site protein sequence of Staphylococcal enterotoxins in the relevant literature, and MHCII-D10 was to link MHCII sequence with TCR-D10 sequence using linker (G4S)3 linking peptide. These capture molecules were shown to effectively bind to seven types of toxins and to capture SEs in various matrices. The digestion time, ratio, and temperature were further optimized, reducing the overall digestion time to just 2 h. The specificity, linearity, sensitivity, precision (RSD%), and recovery of the two methods were verified by liquid chromatography–mass spectrometry. When the MHCII and MHCII-D10 captured the toxins, the limit of quantification (LOD) in the 1 × PBS, plasma, and milk matrices ranged from 1.5625 to 100 fmol/µL, with the recovery rate ranging from 18.4% to 96%. The design of these capture molecules eliminates the need for animal-specific immunization, simplifying the pre-detection process and avoiding ethical concerns. This development holds significant promise for clinical diagnosis and reference.

Mechanisms of tumor immunosuppressive microenvironment formation in esophageal cancer.

As a highly invasive malignancy, esophageal cancer (EC) is a global health issue, and was the eighth most prevalent cancer and the sixth leading cause of cancer-related death worldwide in 2020. Due to its highly immunogenic nature, emer-ging immunotherapy approaches, such as immune checkpoint blockade, have demonstrated promising efficacy in treating EC; however, certain limitations and challenges still exist. In addition, tumors may exhibit primary or acquired resistance to immunotherapy in the tumor immune microenvironment (TIME); thus, understanding the TIME is urgent and crucial, especially given the im-portance of an immunosuppressive microenvironment in tumor progression. The aim of this review was to better elucidate the mechanisms of the suppressive TIME, including cell infiltration, immune cell subsets, cytokines and signaling pathways in the tumor microenvironment of EC patients, as well as the downregulated expression of major histocompatibility complex molecules in tumor cells, to obtain a better understanding of the differences in EC patient responses to immunotherapeutic strategies and accurately predict the efficacy of immunotherapies. Therefore, personalized treatments could be developed to maximize the advantages of immunotherapy.

Exploring Iodide and Hydrogen Sulfide as ROS Scavengers to Delay Acute Rejection in MHC-Defined Vascularized Composite Allografts

Vascularized composite allografts (VCA) face ischemic challenges due to their limited availability. Reperfusion following ischemia triggers oxidative stress and immune reactions, and scavenger molecules could mitigate ischemia–reperfusion injuries and, therefore, immune rejection. We compared two scavengers in a myocutaneous flap VCA model. In total, 18 myocutaneous flap transplants were performed in Major histocompatibility complex (MHC)-defined miniature swine. In the MATCH group (n = 9), donors and recipients had minor antigen mismatch, while the animals were fully mismatched in the MISMATCH group (n = 9). Grafts were pretreated with saline, sodium iodide (NaI), or hydrogen sulfide (H2S), stored at 4 °C for 3 h, and then transplanted. Flaps were monitored until clinical rejection without immunosuppression. In the MATCH group, flap survival did not significantly differ between the saline and hydrogen sulfide treatments (p = 0.483) but was reduced with the sodium iodide treatment (p = 0.007). In the MISMATCH group, survival was similar between the saline and hydrogen sulfide treatments (p = 0.483) but decreased with the sodium iodide treatment (p = 0.007). Rhabdomyolysis markers showed lower but non-significant levels in the experimental subgroups for both the MATCH and MISMATCH animals. This study provides insightful data for the field of antioxidant-based approaches in VCA and transplantation.

Shedding light on the role of LAG-3 in hepatocellular carcinoma: unraveling immunomodulatory pathways

Hepatocellular carcinoma (HCC) stands as a primary malignant liver tumor characterized by chronic inflammation and complex alterations within the tumor microenvironment (TME). Lymphocyte activation gene 3 (LAG-3), also known as CD223, has gained prominence as a potential next-generation immune checkpoint, maintaining continuous expression in response to persistent antigen exposure within the TME, warranting our attention. In patients with HCC, LAG-3 expression on T cells, regulatory T cells (Tregs), and natural killer (NK) cells contributes to immune evasion, while high expression of LAG-3 leads to increased angiogenesis and poor prognosis. By interacting with major histocompatibility complex class II molecules, LAG-3 promotes T cell exhaustion and suppresses antitumor responses, often in collaboration with other immune checkpoints like programmed cell death protein 1 (PD-1), while on Tregs and NK cells, LAG-3 modulates their suppressive functions, indirectly facilitating tumor immune escape. LAG-3 expression may offer prognostic insights, correlating with disease progression and outcomes in HCC patients, while various preclinical studies highlight the potential of LAG-3-targeted therapies in reinvigorating immune responses against HCC, with a few combination approaches targeting LAG-3 alongside other checkpoints demonstrating synergistic effects in restoring T cell function. Therefore, harnessing LAG-3 as a therapeutic target holds promise for enhancing antitumor immunity and potentially improving HCC treatment outcomes. Our narrative review aims to delve into the full spectrum of LAG-3 signaling in HCC, with the goal of a better understanding of the pathophysiological and immunological basis of its use to arrest HCC growth and development.

Chaperone-mediated MHC-I peptide exchange in antigen presentation.

This work focuses on molecules that are encoded by the major histocompatibility complex (MHC) and that bind self-, foreign- or tumor-derived peptides and display these at the cell surface for recognition by receptors on T lymphocytes (T cell receptors, TCR) and natural killer (NK) cells. The past few decades have accumulated a vast knowledge base of the structures of MHC molecules and the complexes of MHC/TCR with specificity for many different peptides. In recent years, the structures of MHC-I molecules complexed with chaperones that assist in peptide loading have been revealed by X-ray crystallography and cryogenic electron microscopy. These structures have been further studied using mutagenesis, molecular dynamics and NMR approaches. This review summarizes the current structures and dynamic principles that govern peptide exchange as these relate to the process of antigen presentation.